White balance adjusting system for a color image pickup apparatus

Claim 2

A system according to claim 1 wherein said means for holding is a counter (9r, 9b; 93, 94) which is counted up or down according to increase or decrease in said white balance control signal.

Claim 3

A system according to claim 2 wherein said system further comprises means (71, 72, 91; 73, 74, 92) for controlling said counter (93, 94) so that said counter (93, 94) does not respond to increase or decrease in the level of said white balance control signal within a predetermined range.

Claim 4

A system according to claim 3 wherein said means for controlling said counter consists of two comparator circuits (71, 72; 73, 74) which output signals that control count up or count down of counter (93, 94), and said white balance control signal is applied to one of input terminals of each of the two comparator circuits while reference voltages of different values are supplied to the other of input terminals, and the range of said white balance control signal level in which said counter does not respond is determined by the difference in values of said reference voltages.

Claim 5

A system according to claim 1 wherein said system further comprises means for feeding back a signal corresponding to said data held by said means for holding to said means for detecting the deviation from white, and means for changing a white balance reference point for detecting deviation from white based on the fed-back signal.

Claim 6

A white balance adjusting system for a color image pickup apparatus comprising: means (107) for detecting a white portion in a picture based on a color information signal (R-B, R+B-2Y) and a luminance information signal (Y) of a picture picked up by an image sensor (1); means (105, 114) for extracting a signal portion which corresponds to the white portion from the color information signal of the picture based on the detection signal supplied from said means for detecting white portion; means (106, 116) which detects a deviation from white in the picture picked up based on the white portion signal that has been extracted and generates a white balance control signal based on the results of detection; and means (3r, 3b) for controlling a gain of color signal in an image signal which expresses said picture based on the white balance control signal that has been generated; wherein the threshold for detecting the white portion from one of said luminance information signal and said color information signal is variable.

Claim 7

A system according to claim 6 wherein the variable threshold for detecting said white portion from said luminance information signal is generated from said color information signal.

Claim 8

A system according to claim 6 wherein the variable threshold for detecting said white portion from said color information signal is generated from said luminance information signal.

Claim 9

A white balance adjusting system for a color image pickup apparatus which includes an image sensor (1), a signal processing circuit (2) that generates a luminance signal (Y), a red color signal (R) and a blue color signal (B) from a picture signal supplied from the image sensor, a first variable gain amplifier (3r) that amplifies the red color signal (R), a second variable gain amplifier (3b) that amplifies the blue color signal (B), and a matrix circuit (4) that generates two color-difference signals (R-Y, B-Y) from the red color signal (R) which is output from the first variable gain amplifier, the blue color signal (B) which is output from the second variable gain amplifier and the luminance signal (Y) which is output from the signal processing circuit, said system comprising: means of subtraction (102) that generates a signal of remainder (R-B) of the two color-difference signals (R-Y, B-Y); means of addition (103) that generates a signal of sum (R+B-2Y) of the two color-difference signals (R-Y, B-Y); means (107) for detecting a white portion in a picture that has been picked up based on two signals among the remainder signal (R-B), the sum signal (R+B-2Y) and the luminance signal (Y); means (104) for extracting a signal portion that corresponds to the white portion from said remainder signal based on the detection signal supplied from said means for detecting the white portion; means (114) for extracting a signal portion that corresponds to the white portion from said sum signal based on the detection signal supplied from said means for detecting the white portion; means (105) for generating an averaged remainder signal by integrating the remainder signal of the extracted white portion; means (115) for generating an averaged sum signal by integrating the sum signal of the extracted white portion; means (106) for generating a first white balance control signal by comparing the averaged remainder signal with a reference voltage; means (116) for generating a second white balance control signal by comparing the averaged sum signal with a reference voltage; means (108) for generating gain control signals that control gains of said first and second variable gain amplifiers from the first and second white balance control signals, respectively; wherein one of the two signals selected from said remainder signal (R-B), said sum signal (R+B-2Y) and said luminance signal (Y) is used as threshold for detecting the white portion from the other signal.

Claim 10

A system according to claim 9 wherein said remainder signal (R-B) is used as threshold for detecting the white portion from said luminance signal (Y).

Claim 11

A system according to claim 9 wherein said luminance signal (Y) is used as threshold for detecting the white portion from said remainder signal (R-B).